chromium/third_party/angle/src/compiler/translator/tree_util/RunAtTheEndOfShader.cpp

//
// Copyright 2017 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// RunAtTheEndOfShader.cpp: Add code to be run at the end of the shader. In case main() contains a
// return statement, this is done by replacing the main() function with another function that calls
// the old main, like this:
//
// void main() { body }
// =>
// void main0() { body }
// void main()
// {
//     main0();
//     codeToRun
// }
//
// This way the code will get run even if the return statement inside main is executed.
//
// This is done if main ends in an unconditional |discard| as well, to help with SPIR-V generation
// that expects no dead-code to be present after branches in a block.  To avoid bugs when |discard|
// is wrapped in unconditional blocks, any |discard| in main() is used as a signal to wrap it.
//

#include "compiler/translator/tree_util/RunAtTheEndOfShader.h"

#include "compiler/translator/Compiler.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/StaticType.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/tree_util/FindMain.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{

namespace
{

constexpr const ImmutableString kMainString("main");

class ContainsReturnOrDiscardTraverser : public TIntermTraverser
{ … };

bool ContainsReturnOrDiscard(TIntermNode *node)
{ … }

void WrapMainAndAppend(TIntermBlock *root,
                       TIntermFunctionDefinition *main,
                       TIntermNode *codeToRun,
                       TSymbolTable *symbolTable)
{ … }

}  // anonymous namespace

bool RunAtTheEndOfShader(TCompiler *compiler,
                         TIntermBlock *root,
                         TIntermNode *codeToRun,
                         TSymbolTable *symbolTable)
{ … }

}  // namespace sh